looks like some bugs persists in the latest FB2K Mobile update a week ago such that

1. when FB2k is playing in background, a new notification comes (due to text, call, vendor promotion, app msg or just app update notification) even without sound (tried both DND and vibration only) can crash FB2K and stop the playback. this may not happen 100% of the time, but is frequent enough such that I have to deal with this at least once a day

2. when FB2k is playing in background, FB2K doesn't update track info. this means if you switch current foreground application to read email then come back to FB2K, FB2K will not display current playing track info. FB2K will display the previous track info from when you put it to background (when email app was brought to foreground)

2a. in this state, you have to bring FB2K into foreground (current viewing/using app), then put it into STOP playback mode, and then start playback to get FB2K to display correct track info. PAUSE playback never helped when I tried. this means you have to navigate into FB2K configuration view because that's the only place I can find STOP. playback UI only has PAUSE/PLAY